What are the characteristics of the Solar System that lead to the origins of life?

The possibility of finding life elsewhere is for many people the most compelling reason for humankind to explore beyond the Earth. We believe that liquid water and carbon are required for life to arise and thrive, as well as a source of energy. Many places in the Solar System provide these, at least for a time; not only planets, but also some moons and even certain comets. But for life to arise we presume that a hospitable environment must be more than just transient.

The Earth is in the continuously habitable zone, meaning at our size and at our distance from the Sun water has been stable at the surface even though the brightness of the Sun has varied. Not all planets are so lucky. We now know that there once was liquid water on the surface of Mars, but was it there long enough for life to develop? We are not sure, but its possible and if so then life might still linger beneath the surface, perhaps in a place where sub-surface heat meets the surface permafrost. There are other places where there has been liquid water for as long as on Earth. Jupiter's icy moon Europa almost certainly has a liquid water ocean beneath the surface even though its five times further from the Sun than we are. If there are hydrothermal vents at the bottom of Europa's ocean, then that would seem a very hospitable place for life, but that doesn't mean its there. The only way we are going to find out is by going there. Other moons that may have liquid water deep below the surface include Jupiter's moons Callisto and Ganymede as perhaps Saturn's moons Titan and Enceladus.

The Dawn mission intends to orbit Vesta and Ceres, two of the largest asteroids in the solar system. According to current theories, the very different properties of Vesta and Ceres are the result of the asteroids being formed and evolving ...

The Mars Exploration Rover Opportunity was originally designed for a 90 Sol mission (a Sol, one Martian day, is slightly longer than an Earth day at 24 hours and 37 minutes). Its mission has been extended several times as it ...

Mars Exploration Rover Spirit landed in Gusev crater on Mars in January 2004. The rover carries a sophisticated set of instruments that allow it to search for evidence of liquid water that may have been present in the planet's past. ...

Mars Global Surveyor is returning an unprecedented amount of data regarding Mars' surface features, atmosphere, and magnetic properties. Scientists are using the data gathered from this mission both to learn about the Earth by comparing it to Mars, and to ...